Circle divider



July 8, 1969 L|PsKL 5 ET AL 3,453,738

CIRCLE DIVIDER Filed Jan. 22, 1968 Sheet of 2 M/TCHELL L/PSK/s/r. THOMAS ROMANEK 4 TTURNE Y5 July 8 1969 M. LIPSKI. SR, ET AL 3,453,738

CIRCLE DIVIDER Filed Jan. 22, 1968 Sheet 3 of 2 INVENTORS 53 M/ TCHELL L/PSK/ m BY 4* THOMAS ROMANEK A TTORNE Y5 United States Patent 3,453,738 CERCLE DIVIDER Mitchell Lipski, Sr., 5270 W. 90th St., Oak Lawn, Ill. 60453, and Thomas Romanek, 5208 S. Troy St., Chicago, Ill. 60632 Filed Jan. 22, 1968, Ser. No. 699,636 Int. Cl. B431 9/08, 9/12 US. Cl. 3375 9 Claims ABSTRACT OF THE DISCLOSURE A precision indexing circle divider instrument having a base, a rotor provided with an annular series of perforations, and a stop projecting from the base. A stylus may be inserted in any one of a plurality of perforations and used to rotate the rotor until the stylus engages the stop whereby successive operations of this character index a straight edge at successive angles corresponding to the perforations, and lines may be scribed along the straight edge which would be at those angles relative to each other. The base is provided with resilient buttons to prevent slippage when the base is held against the surface on which the lines are marked.

Background of the invention Circle dividers have heretofore been patented as evidenced in U.S. Patent Nos. 411,741, 1,062,740, 1,082,377 and 1,350,273. The prior devices shown in these patents however depend upon the matching of index lines by eyesight which is inaccurate, or by detent means which is not as economically produced or as readily actuated with precision as our herein desclosed indexing circle divider.

One object of the invention is to provide a divider assembly comprising a base in which a rotor is mounted and provided with a straight edge for drawing lines at various angles to each other.

Another object is to provide an indexing plate having a plurality of annular series of perforations which pass under a stop projecting from the base so that a stylus, pencil point or the like inserted into any one of the perforations may be used to rotate the rotor until a stop is engaged whereupon a line may be scribed or drawn along the straight edge, the stylus then being used by inserting it into successively additional perforations to orient the straight edge at the various angles and each time a line may be scribed or drawn so that the lines will then be at angles which equally divide a circle into as many parts as there are perforations in the particular annular series of perforations being utilized.

Another object is to provide an indexing circle divider type of instrument so constructed as to have a minimum number of parts which may be molded of plastic material, die cast from metal or the like for economy of production; and which comprises only five parts, a base, a

rotor, a cover plate to retain the rotor in the base and an interchangeable index plate in addition to the stop element, as many index plates being provided as desired for dividing circles into equal numbers of parts or into degrees if desired.

A further object is to provide an assembly which permits mounting of the stop in a recess of the base to be held therein when the cover plate is secured to the base, resilient buttons being carried by the base and retained in position by the cover plate, and the stop being so designed that index plates can be readily interchanged without interference thereby.

Still another object is to provide the straight edge so related to the resilient buttons that the instrument may be held against a surface without slippage due to the resilient buttons engaging such surface, the straight edge being substantially in contact with that surface for the scribing or drawing of lines along the straight edge.

An additional object is to provide a. base so designed that a rotor may rotate therein and be retained by the cover plate which has an opening through which the stop extends to a position therea'bove, thus providing a space to receive the index plate so that the perforations thereof can rotate under the stop and the stop will intercept a stylus entered into a perforation and used to rotate the rotor.

Brief summary of the invention A rotor is carried by a base and retained by a cover plate in such manner that interchangeable index plates can be secured to the rotor. Each index plate is provided with several annular series of perforations adapted for receiving a stylus which is then operated to rotate the index plate until the stylus engages a stop projecting from the base above the index plate.

With the foregoing and other objects in view, our invention consists in the construction, arrangement and combination of the various parts of our indexing circle divider, whereby the objects above contemplated are attained, as hereinafter more fully set forth, pointed out in our claims and illustrated in detail on the accompanying drawings, wherein:

Brief description of the drawings FIG. 1 is a plan view of our indexing circle divider instrument with portions of the index plate and cover plate broken away to show cooperating details of the various parts of the instrument.

FIG. 2 is a vertical sectional view on the line 2-2 of FIG. 1.

FIG. 3 is a horizontal sectional view on the line 33 of FIG. 1.

FIG. 4 is a horizontal sectional view on the line 44 of FIG. 1.

FIG. 5 is a top plan view of a portion of the base of our instrument.

FIG. 6 is a top plan view of a portion of the rotor of our instrument.

FIG. 7 is a top plan view of a portion of a different index plate than the one shown in FIG. 1; and

FIG. 8 is a perspective view of a stop used in our instrument.

On the accompanying drawings we have used reference characters to indicate in general the five parts of our indexing circle divider instrument as follows:

B-base C-cover plate Rrotor IP-index plate Sstop Referring to FIGS. 1 and 5 the base B of the shape shown in FIG. 5 has an inner diameter 10 which is annularly shouldered by a larger diameter indicated at 12. The base B has six tapped holes 14, four shouldered holes 16 and two shouldered holes 18. It also has a recess 20 and a tapped hole 22.

Referring to FIGS. 1 and 6 the rotor R has an inner diameter 27, an outer diameter 24 to rotatably fit the diameter 12 and a pair of shoulders 26 and 28 (see FIG. 2). The shoulder 26 rotatably fits the inner diameter 10 of the base B. The rotor R further has a web 30 terminating in a straight edge 32 adjacent the center of the instrument and the straight edge is provided with a center notch 34. The rotor also has three tapped holes 29.

The cover plate C is the same shape as the base B and has six countersunk holes 36 (one of them shown near 3 the bottom of FIG. 2) matching the tapped holes 14, a stop shank hole 38 and an inner diameter 40 in which the shoulder 28 of the rotor R rotates. The index plate IP has an inner diameter 42 substantially coincident with the inner diameter 27 of the rotor R, and the outer diameters of the base, cover plate and index plate substantially coincide as shown in FIGS. 2 and 3. The index plate is also provided with three countersunk holes 44 matching the tapped holes 29 of the rotor R, and with a number of perforations 46 which will be described in more detail later.

The stop S comprises a flange 48 from which a shank 50 extends and which terminates in a laterally extending stop arm 52. The flange is notched at 53 for a purpose which will hereinafter appear.

Our indexing circle divider is assembled by placing four small flanged stop buttons 54 of resilient material such as plastic, neoprene, or rubber in the shouldered holes 16 and two larger ones 56 in the shouldered holes 18; then placing the rotor R in position so that it can be secured by the cover plate C. The stop S shown in FIG. 8 is so designed that it can be inserted through the stop shank hole 38 of the cover plate C to the position shown in FIG. 2, and when the cover plate is then placed in position, the flange 48 will be received in the recess 20 of the base B. Eight countersink screws 58 are then entered through the countersunk holes 36 of the cover plate and screwed into the tapped holes 14 of the base B and the instrument is thereby assembled with the exception of adding an index plate IP and a countersink screw 60 shown in FIG. 2 to enter the notch 53 of the stop arm 52. Instead of the screw 60, the base B may be molded with a projection to fit the notch 53, or the recess 20 may be formed otherthan-round, and the flange 48 of a comparable shape.

With respect to the index plates IP, several may be provided and they are interchangeably mounted on the rotor R by means of three countersink screws 62 through the countersunk holes 44 of the index plate and into the tapped holes 29 of the rotor R.

The perforations 46 of each index plate IP may be arranged in a plurality of annular series such as for a No. 1 index plate shown in FIG. 1 wherein the outer annular series is divided into sixteen equal spaces and the inner one into twenty equal spaces, the intervening perforations being for seventeen, eighteen and nineteen equal divisions of a circle. Similarly a No. 2 plate may have perforations from 21 to 25 and a No. 3 from 26 to 30 (by way of example). A No. 4 plate such as shown in FIG. 7 may be for 360 (in one degree increments) and in five annular series, the degrees being indicated such as etc. up to and including 355 as illustrated. Obviously, other index plates with other desired divisions may be provided as desired or required.

Practical operation Referring to FIG. 1 it will be noted that one of the perforations 46 (specifically the perforations 46a adjacent the stop S) indicates that a suitable stylus, pencil point or ball point may be inserted into this perforation when it is spaced from the stop S, and then the pencil used to rotate the rotor R counterclockwise (arrow 47) until the pencil engages the stop S as at 46a. A line may then be drawn along the straight edge 32 onto a surface indicated at 64 in FIGS. 2 and 3 such as a sheet of paper or the like. The instrument is held down so that the stop buttons 54 and 56 frictionally engage the surface 64, and the straight edge 32 of the web 30 is adjacent this surface and spaced from a center line so that a pencil drawn along the straight edge will fall on the geometrical center line of the instrument. The pencil may then be removed and entered into the next perforation 56 in the annular series thereof in order to divide the circle into sixteen equal parts, and after being engaged with the stop S another line can be drawn along the straight edge and so on. Obviously, if the circle is to be divided into eight parts, every other perforations is used instead of every one. Likewise,

4 it is obvious how the circle can be divided into other equal parts depending on the index plate used, or into degrees if using the index plate No. 4 which in effect may be utilized to divide the circle into 360 equal parts.

The matter of changing from one index plate to the other involves merely the removal of the three screws 62 and the index plate, the substitution of another index plate and the replacement of these three screws.

From the foregoing specification it will be obvious that we have provided an instrument of the indexing circle divider type which is relatively simple and economical to manufacture when molded of plastic material, is easily assembled and can be used for dividing circles into dilferent numbers of equal parts by a simple index plate changing arrangement.

The resilient buttons 54 and 56 may be of magnetic rubher to cooperate with a magnetic surface on which a sheet of paper is placed under the instrument, thus eliminating the necessity of requiring manual pressure to hold the instrument against slipping on the paper. Such magnetic rubber is sold under the trademark Magnarubber.

It will be obvious that we have provided an instrument which may divide a circle by indexation with extreme accuracy as to the position of the straight edge 32 at each index point. Accordingly, a Simple mathematical computation can be made, or followed by a chart system if need be, to create any angular position around a 360 circle or part of a circle to be scribed or drawn in reference to a line. The main intention is to simplify accurate movements for educational purposes. However, other needs and uses prove themselves for practical purposes, and interest is created in a mathematical maneuver, thereby opening doors for further education.

Our instrument may be made of any suitable size, shape or material as is obvious, the base B and the cover C be- 1ng provided with a straight edge 68 for impingement agamst a T-square, triangle, straight edge of drafting machine or the like if desired.

Desired results are quickly and easily attained by the use of our instrument and accurate division of circles is obtained in a facile manner by the simplified type of indexing operation provided. The entire unit is compact and light, and all parts are readily accessible to achieve easy ndexation. A simple and quick assembly of the parts is inherent in the construction illustrated.

The straight edge 32 provides a solid line type of di vlder, and the notch 34 a positive and accurate center. The device is also readily adaptable to vernier scales if desired for greater accuracy and additional division increments. The instrument is particularly suitable for educatlonal purposes and mathematics, and is of simple construction involving a minimum of parts. It is also versat1le for a variety of uses in schools and general industry. On hand manueverability is inherent in the instrument and it can be used for right or left hand operation a the stop arm 52 is of symmetrical design.

Some changes may be made in the construction and arrangements of the parts of our disclosed instrument without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims any modified forms of structure or use of mechanical equivalents which may reasonably be included Within their scope.

We claim as our invention:

1. In an indexing circle divider, a base, a rotor mounted in said base for rotation relative thereto, an indexing plate mounted on said rotor for rotation therewith, a stop mounted on said base and extending across said index plate, said index plate having an annular series of perforations which pass under said stop upon rotation of said rotor whereby a stylus inserted into any one of said perforations may be used to rotate said rotor until said stylus engages said stop. and said rotor having a diametrically extending straight edge instrumental in the drawing of lines at various angles corresponding to said annular series of perforations.

2. An indexing circle divider according to claim 1 wherein a cover plate is secured to said base to retain said rotor mounted in said base.

3. An indexing circle divider according to claim 1 wherein said index plate is removably secured to said rotor and thereby interchangeable with other index plates having different numbers of perforations in their series of perforations.

4, An indexing circle divider according to claim 2 wherein, said index plate is removably secured to said rotor and is thereby interchangeable with other index plates having different numbers of perforations in their annular series of perforations.

5. An indexing circle divider according to claim 1 wherein said index plate has a plurality of said annular series of perforations with a different number of perforations in each annular series.

6. An indexing circle divider according to claim 3 wherein one of said index plates has a plurality of annular series of perforations at one degree intervals.

7. An indexing circle divider according to claim 2 wherein said base has a plurality of shouldered openings spaced therearound near its periphery, and flanged resilient buttons received therein, retained by said cover plate and having portions projecting below the lower surface 1 of said base.

8. An indexing circle divider according to claim 7 wherein said straight edge projects below the lower surface of said base to substantially contact a surface against 1y, said base having a recess for said annular flange, said cover plate having an opening through which said stop arm projects, and means to fix said stop arm against rotation of said flange in said recess.

References Cited UNITED STATES PATENTS 344,676 6/ 1886 Ourdan.

411,741 9/1889 Dow 33-75 607,158 7/ 1898 Burnett 3326 1,637,933 8/ 1927 Galvin 33-75 HARRY N. HAROIAN, Primary Examiner. 

